Why have certain chest tube must suction?

Certain chest tubes require suction to help re-expand the lung and facilitate the drainage of air or fluid from the pleural space. Suction can create a negative pressure that aids in overcoming any barriers to lung expansion, such as fluid accumulation or trapped air. This is especially important in cases of pneumothorax or significant pleural effusion, where passive drainage may not be sufficient for effective treatment. The use of suction helps maintain a continuous flow and promotes optimal healing.